/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jmx.access;

import org.springframework.aop.framework.ProxyFactory;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.jmx.MBeanServerNotFoundException;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;

/**
 * Creates a proxy to a managed resource running either locally or remotely.
 * The "proxyInterface" property defines the interface that the generated
 * proxy is supposed to implement. This interface should define methods and
 * properties that correspond to operations and attributes in the management
 * interface of the resource you wish to proxy.
 *
 * <p>There is no need for the managed resource to implement the proxy interface,
 * although you may find it convenient to do. It is not required that every
 * operation and attribute in the management interface is matched by a
 * corresponding property or method in the proxy interface.
 *
 * <p>Attempting to invoke or access any method or property on the proxy
 * interface that does not correspond to the management interface will lead
 * to an {@code InvalidInvocationException}.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @see MBeanClientInterceptor
 * @see InvalidInvocationException
 * @since 1.2
 */
public class MBeanProxyFactoryBean extends MBeanClientInterceptor
        implements FactoryBean<Object>, BeanClassLoaderAware, InitializingBean {

    @Nullable
    private Class<?> proxyInterface;

    @Nullable
    private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

    @Nullable
    private Object mbeanProxy;


    /**
     * Set the interface that the generated proxy will implement.
     * <p>This will usually be a management interface that matches the target MBean,
     * exposing bean property setters and getters for MBean attributes and
     * conventional Java methods for MBean operations.
     *
     * @see #setObjectName
     */
    public void setProxyInterface(Class<?> proxyInterface) {
        this.proxyInterface = proxyInterface;
    }

    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        this.beanClassLoader = classLoader;
    }

    /**
     * Checks that the {@code proxyInterface} has been specified and then
     * generates the proxy for the target MBean.
     */
    @Override
    public void afterPropertiesSet() throws MBeanServerNotFoundException, MBeanInfoRetrievalException {
        super.afterPropertiesSet();

        if (this.proxyInterface == null) {
            this.proxyInterface = getManagementInterface();
            if (this.proxyInterface == null) {
                throw new IllegalArgumentException("Property 'proxyInterface' or 'managementInterface' is required");
            }
        } else {
            if (getManagementInterface() == null) {
                setManagementInterface(this.proxyInterface);
            }
        }
        this.mbeanProxy = new ProxyFactory(this.proxyInterface, this).getProxy(this.beanClassLoader);
    }


    @Override
    @Nullable
    public Object getObject() {
        return this.mbeanProxy;
    }

    @Override
    public Class<?> getObjectType() {
        return this.proxyInterface;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

}
